In digital video services such as satellite or cable digital television, video and audio encoders may be co-located while the associated decoders may or may not be co-located. In these applications, a fixed number of different video channels may be encoded and transmitted together, and bit-rate for each channel may be controlled by a central multiplexing unit.
The MPEG-1, MPEG-2 and MPEG-4 audio and video coding standards may support various multiplexing mechanisms for combining bit streams from up to, for example, 32 audio, 16 video, many video objects and any number of auxiliary streams. The channel rates utilized for transmission or retrieval from storage are not limited to being constant, but may also be variable. Transmission of bit streams may occur across a leased line or across a packet-switched public network, for example. Retrieval of bit streams may be from a DVD ROM database with a bursty data rate, for example. However, implementation architectures of multiplexing may not be provided in these standards.
When multiple streams of data are multiplexed, it may be essential that data is not lost by encoder and/or decoder buffer overflow or underflow. One obvious solution to this problem may involve increasing a buffer size of the buffers that are utilized in the system. However, increasing the buffer size in the system may be cost prohibitive, especially for low-cost transcoders. Additionally, data may be lost if the system has a variable transmission or retrieval rate. Therefore, it may be desirable to have a systematic approach to predict for preventing, for example, loss of data by encoder and/or decoder overflow and/or underflow for a given application.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.